SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b52248016c6e9a38e2bcedd5687879fbe00be07508049756fc70a3daa08cbd5f' 
  AND token = 'L/WXxFmTerrLgIGzZEXLIs6Gl9uNTMCLMqVbgMWYJ8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}